.nav {
    position: fixed;
    right: 3%;
    top: 50%;
    transform: translateY(-50%);
    width: 100px;
    height: 180px;
    z-index: 999;
    display: none;
    li {
        width: 100px;
        height: 30px;
        background-color: #fff;
        line-height: 30px;
        text-align: center;
        border: 1px solid #ccc;
        list-style: none;
    }
    .active {
        background-color: red;
    }
}